This invention relates to the art of tool posts for machine tools, and more particularly to an improved tool post adapted to securely hold a plurality of tool holders and tools, with the tool post subject to selective rotation to bring any pre-selected tool into a desired working orientation with respect to the work piece to be operated on, and with the tool being held in a desired fixed position with respect to the work piece upon pre-selected positioning of the tool.
A variety of tool posts have in the past been evolved which hold a plurality of tool holders in which tools for operation on a work piece held on a machine tool such as a lathe, may be held. Such previously evolved multiple tool holding tool posts have served to increase the speed and facility with which any given machining operation may be performed in that the set-up time for positioning any given tool with respect to a work piece may be reduced.
It has, however, been found that the previously evolved multiple tool holding tool posts do not succeed in attaining the desired goal of insuring desired rapid and precise positioning of the tool with respect to the work piece, since such previously evolved tool posts generally employ either no locating means, or a locating pin which must mate with a specific hole at a given setting. If there are no positive locating means, the working forces between the work piece and tool result in undesired movement of the tool, disrupting the desired tool setting. Where locating pins are used to fix the position on the tool post, the time required to effect interengagement of the pin with its mating hole, eliminates the desired time saving advantage of the multiple tool holding tool post. Further, clearances required to permit movement of these previously evolved multiple tool holding tool posts to bring a different tool to a working position, and the clearance required to permit positioning of the tool holders on the post are such that attainment of a desired precision of positioning of the tool with respect to the work piece is not always achieved, so that resetting, and readjustment of any given tool held by the tool post is often required after the tool post is rotated to bring the tool into working position. This need for tool resetting increases as the tool post ages, due to wear between relatively moving parts, increasing the play between these parts.